This disclosure generally relates to methods and apparatus for integrating actuators in aircraft flight control systems. In particular, this disclosure relates to methods and apparatus for integrating rotary actuators in flight control systems with thin wings.
It is known to control pivoting movements of limited amplitude between two parts by means of a rotary actuator. Rotary actuators have the advantage of very small overall dimensions, because they can be positioned in accordance with the relative pivoting axis between the two parts. By comparison, the control of the same movement with the aid of a linear actuator makes it necessary to install the linear actuator on one of the parts, approximately perpendicular to the pivoting axis, and to connect the other part with the aid of a mechanism including at least one articulated link.
In particular, it is known to use rotary actuators to control pivoting of aircraft flight control surfaces such as ailerons. An aileron is a hinged flight control surface usually fitted in a pivoting manner to the rear spar of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll. Each aileron has a limited deflection with respect to its median angular position where it is aligned with the wing.
The wings in high-performance aircraft are thin, that is, the distance between the top and bottom of the outer mold line (OML) at the control surface hinge line is small. Thin-wing aircraft create a challenge for spatial integration of actuation control systems with conventional linear piston actuator types. Rotary geared actuators (RGA) and rotary vane actuators (RVA) have been developed and used in thin-wing military aircraft.
Typically, an actuation system is confirmed by laboratory (system verification phase) and flight (aircraft verification phase) tests and the results usually require an adjustment of the stiffness value. It would be desirable to incorporate a feature that can facilitate a change of the component(s) in the load loop of a rotary actuation system and the change should have minimal impact on aircraft production.